HTML5效果：实现树叶飘落

实现如图所示的东西效果（落叶下落）：

html代码：

<!DOCTYPE html>
<html>
<head>
    <title>HTML5树叶飘落动画</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=500px, initial-scale=0.64">
    <link rel="stylesheet" href="leaves.css" type="text/css">
    <script src="leaves.js" type="text/javascript"></script>
</head>
<body>
    <div id="container">
        <div id="leafContainer"></div>
        <div id="message">
            <em>这是基于webkit的落叶动画</em>
        </div>
    </div>
</body>
</html>

css代码：

body
{
    background-color: #4E4226;
}

#container {
    position: relative;
    height: 700px;
    width: 500px;
    margin: 10px auto;
    overflow: hidden;
    border: 4px solid #5C090A;
    background: #4E4226 url('images/backgroundLeaves.jpg') no-repeat top left;
}

#leafContainer {
    position: absolute;
    width: 100%;
    height: 100%;
}

#message{
    position: absolute;
    top: 160px;
    width: 100%;
    height: 300px;
    background:transparent url('images/textBackground.png') repeat-x center;
    color: #5C090A;
    font-size: 220%;
    font-family: 'Georgia';
    text-align: center;
    padding: 20px 10px;
    -webkit-box-sizing: border-box;
    -webkit-background-size: 100% 100%;
    z-index:;
}

em {
    font-weight: bold;
    font-style: normal;
}

#leafContainer > div {
    position: absolute;
    width: 100px;
    height: 100px;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-direction: normal;
    -webkit-animation-timing-function: linear;
}

#leafContainer > div > img {
     position: absolute;
     width: 100px;
     height: 100px;
     -webkit-animation-iteration-count: infinite;
     -webkit-animation-direction: alternate;
     -webkit-animation-timing-function: ease-in-out;
     -webkit-transform-origin: 50% -100%;
}

@-webkit-keyframes fade
{
    0%   { opacity:; }
    95%  { opacity:; }
    100% { opacity:; }
}

@-webkit-keyframes drop
{
    0%   { -webkit-transform: translate(0px, -50px); }
    100% { -webkit-transform: translate(0px, 650px); }
}

@-webkit-keyframes clockwiseSpin
{
    0%   { -webkit-transform: rotate(-50deg); }
    100% { -webkit-transform: rotate(50deg); }
}

@-webkit-keyframes counterclockwiseSpinAndFlip
{
    0%   { -webkit-transform: scale(-1, 1) rotate(50deg); }
    100% { -webkit-transform: scale(-1, 1) rotate(-50deg); }
}

js代码：

const NUMBER_OF_LEAVES = 30;
function init(){
    var container = document.getElementById('leafContainer');
    for (var i = 0; i < NUMBER_OF_LEAVES; i++) {
        container.appendChild(createALeaf());
    }
}

function randomInteger(low, high){
    return low + Math.floor(Math.random() * (high - low));
}

function randomFloat(low, high){
    return low + Math.random() * (high - low);
}

function pixelValue(value){
    return value + 'px';
}

function durationValue(value){
    return value + 's';
}

function createALeaf(){
    var leafDiv = document.createElement('div');
    leafDiv.style.top = "-100px";
    leafDiv.style.left = pixelValue(randomInteger(0, 500));
    leafDiv.style.webkitAnimationName = 'fade, drop';
    var fadeAndDropDuration = durationValue(randomFloat(5, 11));
    leafDiv.style.webkitAnimationDuration = fadeAndDropDuration + ', ' + fadeAndDropDuration;
    var leafDelay = durationValue(randomFloat(0, 5));
    leafDiv.style.webkitAnimationDelay = leafDelay + ', ' + leafDelay;

    var image = document.createElement('img');
    image.src = 'images/realLeaf' + randomInteger(1, 5) + '.png';
    var spinAnimationName = (Math.random() < 0.5) ? 'clockwiseSpin' : 'counterclockwiseSpinAndFlip';
    image.style.webkitAnimationName = spinAnimationName;
    var spinDuration = durationValue(randomFloat(4, 8));
    image.style.webkitAnimationDuration = spinDuration;

    leafDiv.appendChild(image);
    return leafDiv;
}

window.addEventListener('load', init, false);

转载地址：http://www.html5tricks.com/css3-fall-leaves.html